The nature of consciousness remains deeply mysterious and profoundly important, with existential, medical and spiritual implication. We know what it is like to be conscious – to have awareness, a conscious ‘mind’, but who, or what, are ‘we’ who know such things? How is the subjective nature of phenomenal experience – our ‘inner life’ - to be explained in scientific terms? What consciousness actually is, and how it comes about remain unknown. The general assumption in modern science...

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Tuning the Brain-TUS

TUS - Transcranial Ultrasound

Ultrasound consists of megahertz mechanical vibrations, and is widely used for medical imaging. As microtubules have megahertz vibrations, we have been studying ultrasound effects on the brain, delivered non-invasively from the scalp – ‘transcranial ultrasound’ (‘TUS’). We performed the first clinical trial of transcranial ultrasound (TUS) on mental states on human volunteers, finding that 15 seconds of sub-thermal 8 MHz ultrasound applied at the fronto-temporal scalp resulted in 40 minutes of mood improvement compared with placebo.

Two subsequent TUS studies done in collaboration with UA professor of psychology John Allen and post-doc Jay Sanguinetti have shown similar mood improvement from brief, sub-thermal TUS. These studies are currently being written up for publication.

Mood disorders, Alzheimer’s disease, traumatic brain injury (TBI) and post-traumatic stress disorders (PTSD) are enormous problems for those afflicted, their families, caregivers and society in general. Current treatments for these disorders are modestly effective at best, and new, more effective and inexpensive approaches are needed. A major hurdle in treatment is the lack of understanding in mainstream approaches as to how the brain works normally, how mood, cognition, memory and consciousness derive from synaptic computation among neurons. However evidence now suggests mental states may depend, to some extent at least, on vibrations, e.g. sound wave solitons in neuronal membranes, and megahertz (‘MHz’, 106 to 107 Hz) resonances in microtubule networks inside neurons. In TBI and Alzheimer’s disease, microtubules are disrupted and release ‘tau’, a microtubule-associated protein. Under normal circumstances, microtubules are directly responsible for neuronal and synaptic growth, repair and plasticity.

Hypothesis or Objective: High intensity US can heat, cavitate and ablate kidney stones, brain tumors and other tissue. Mid-intensity US (‘diathermy’) causes mild heating, useful for musculoskeletal problems. Low intensity, ‘sub-thermal’ US (<720 mW/cm2 by FDA guidelines) excites peripheral neurons,4 and promotes their regeneration after injury. Applied at the scalp, low intensity TUS is FDA-approved for brain imaging, though supplanted by CT, MRI etc. TUS is still used to image brains of newborn babies through boneless fontanelles, and can be focused anywhere in the adult brain. WJ Tyler and others first showed low intensity TUS caused behavioral and electrophysiological changes in animals, and more recently cognitive enhancement in humans.

In the first TUS study on human mental states,11 our group showed that 15 seconds of 8 MHz TUS to fronto-temporal cortex from temporal scalp at 150 mW/cm2 resulted in 40 minutes of improved mood compared to sham exposure. Further studies12 have shown optimal mood improvement with 2 MHz TUS for 30 seconds to right fronto-temporal cortex. In some cases, vertex stimulation (targeting cingulate cortex) resulted in uncontrolled laughter, "out of body" experiences and feelings of being "more in the moment". High frequency (gamma synchrony) EEG was increased near the TUS stimulation site.

Our previous TUS studies have used a clinical GE Logiq US imaging device, and the U+ single transducer TUS headset from Thync, Tyler’s company (formerly NeuroTrek). Both devices are limited in range of MHz frequencies for testing. We are collaborating with Sterling Cooley (Berkeley Ultrasound, Berkeley, California) who has developed a TUS device called the NeuroResonator 1 (NR1) which we tested and calibrated in October, 2014. Proposed modifications will upgrade to the battery-powered NeuroResonator 2 (‘NR2’) with multiple US piezo transducer/emitters with various lead placements, each emitter controlled individually, able to be aimed at particular brain areas, driven synchronously, sequentially, in any combination and/or pulse modulated, e.g. by music. The NR2 will be calibrated, tested, and reviewed and approved by our Bioengineering and Institutional Review Board. Stimulation sites will be selected based on injured brain area, right fronto-temporal and other areas. We plan pilot studies commencing early spring 2015 and will search for optimal techniques. With the NR2 fitting in an EEG cap, we will also study TUS effects on simultaneous EEG.